Hi Level Track members. I received this question in an email and wanted to ask for your guidance:
We want use Diff. Pressure to measure the level of a tank. My concern is the varying SG (density) of the liquid – in this case fuel (or Bunker) oil, as well as the effects of varying temperature on the oil. Will this seriously affect the accuracy of the transmitter?
Thanks in advance for your help!
Jim,
While DP is still the most widely used instrument to measure level. However, DP wouldn’t be my first choice if the SG and the temperature of my process changes significantly. It seems like that is what you are having with your application. I would consider using radar technology assuming you have opening at the top of your tank.
In reply to Tom Moser:
I sent an email to the person asking the question pointing them to this thread.
I suggested that they join the Emerson Exchange 365 community and this track given the high quality of wisdom shared! ;-)
In reply to Jim Cahill:
When you have an application with varying specific gravity, the differential pressure level measurement will be affected by the changes in the specific gravity. Depending on the application, it could be better to use a radar device to measure the level instead as it is not affected by changes in the specific gravity. It depends on the measurement accuracy requirements, the process conditions, and the specifics of your tank. If you are more comfortable with using Differential Pressure, you may find that with your application, differential pressure can get you the level measurement that you need. But taking a look at what radar could do for you given the changes in specific gravity would be recommended.
If you did decide that radar would be better for your application but are limited by side connections on your tank, as long as you have a top side connection, you could use guided wave radar with a long stud which would help hold the probe away from the tank wall. You would also want to use a centering disk to hold the probe away from the tank wall at the bottom of the probe as well.
Jim, When you have an application with varying specific gravity, the differential pressure level measurement will be affected by the changes in the specific gravity. Depending on the application, it could be better to use a radar device to measure the level instead as it is not affected by changes in the specific gravity. It depends on the measurement accuracy requirements, the process conditions, and the specifics of your tank. If you are more comfortable with using Differential Pressure, you may find that with your application, differential pressure can get you the level measurement that you need. But taking a look at what radar could do for you given the changes in specific gravity would be recommended. If you did decide that radar would be better for your application but are limited by side connections on your tank, as long as you have a top side connection, you could use guided wave radar with a long stud which would help hold the probe away from the tank wall. You would also want to use a centering disk to hold the probe away from the tank wall at the bottom of the probe as well.